Magnetic resonance neurography: Preoperative assessment of facial nerve invasion in malignant parotid gland tumors.

Backgrounds: Facial nerve invasion (FNI) in parotid gland malignancies significantly impacts treatment outcomes and prognosis. Accurate preoperative assessment of FNI is crucial for surgical planning and tumor staging. Conventional imaging modalities often fail to visualize the facial nerve and assess FNI.

Objects: This study aims to evaluate the predictive efficacy of magnetic resonance neurography (MRN) in detecting FNI in parotid gland malignancies, with the goal of aiding tumor staging and treatment decision-making.

Methods: 28 patients with parotid gland malignancies were included. MRN was utilized to visualize the intraparotid facial nerve and determine its relationship with the tumor. MRN results were then used to predict FNI and re-evaluate the clinical T stage. Surgical records were used for validation. Statistical analysis was performed using chi-square tests and net reclassification improvement (NRI).

Results: The display rates of the main trunk and other divisions (temporofacial and cervicofacial) of the intraparotid facial nerve were 100 %, 96.4 %, and 96.4 %, respectively. Twenty-three patients (82.1 %) matched the surgical findings (P < 0.01). MRN-indicated infiltration performed better than facial paralysis in predicting FNI. Tumors of stage T4a were underestimated in 22.7 % of cases (n = 5), and evaluation of clinical T stage with MRN was superior to that without MRN (NRI > 0, Z = 2.17, P = 0.03).

Conclusions: MRN can provide valuable information for predicting FNI in parotid gland malignancies, thereby improving tumor staging and aiding treatment decision-making.